Heat-conducting system



Patented June 10, 1930 PATENT OFFICE RALPH H. CHURCHILL,

OF CHICAGO, ILLINOIS HEAT-CONDUCTIN G SYSTEM No Drawing.

tures and will remain sufiiciently mobile at low temperature to circulate readily. Such 10 a medium is particularly well adapted to serve as a cooling element for an internal 7 combustion engine, especially in an automotive vehicle, though obviously its usefulness is not confined to this class of work. The invention consists in certain elements or ingredients combined as hereinafter described and as indicated in the claims. As is well understood, the water commonly employed in a circulatory system used for cooling an internal combustion engine, as in an automobile or aeroplane, will freeze at ordinary winter temperatures, and heretofore it has been common practice to add a certain proportion of alcohol to the water to lower the freezing point or to use glycerine for the same purpose. The alcohol has the disadvantage of evaporating readily and thus separating from the water, leaving a mixture of unknown properties Whose freezing point is constantly rising as the alcohol is graduall eliminated; glycerine, on the other han while it does not evaporate readily, is comparatively expensive, and is not a particularly good conductor of heat. well known that mineral oils, including various grades of petroleum, have a low freezing point, a high boiling point, and can be circulated readily enough in a cooling system, but they are also poor conductors of heat, and the use bf any such oil alone would tend to permit undesirably high temperatures for the operation of an engine. This invention undertakes to employ an oil such as kerosene or other thin petroleum product which is preferably cheaper than glycerine as the principal circulating element, but compensates for its poor heatconducting qualities by providing a quan- 5 tity of finely-divided material distributed It is also.

Application filed November 15, 1926. I Serial No. 148,612.

found that finely-divided aluminum is quite effective for this purpose, since its heat conductivity is relatively high and its presence in fine particles in the oil assists in the rapid absorption of heat from the cylinder walls of the engine and in the equally eflective radiation of the heat when the cooling medium reaches the radiator. It will be evident to those skilled in the sciences of chemistry and physics that other solid materials than aluminum may be employed. For, example, magnesium in finely divided form would also be satisfactory, except that it is less plentiful and therefore more expensive than aluminum. Of the metals, it will be understood that the relatively lighter ones are preferred because they are more effectively held in suspension in the liquid.

However, where it is necessary to keep the liquid somewhat agitated and in constant circulation in order to maintain proper distribution of the finely-divided metal through the liquid vehicle, this is accomplished in the usual cooling system by means of a circulating pump which operates Whenever the engine is running, but when the engine stops andthe pump ceases to Work, there may be a tendency for the metal particles to settle through the oil to the lower points in the system or into any pockets which may be present in the cylinder jackets of the engine. Being very finely divided, the metallic particles will then tend to pack as they settle, so that they will not be readily taken up by the liquid when the circulation is resumed. I have dis covered, however, that by adding to the oil a small quantity of glycerine or sugar solution or honey, or perhaps some other liquid substance of greater density than the oil itself, the packing of the metal may be prevented because the glycerine or other heavy liquid settles through the oil more rapidly than the metal and fills the low points of the system and the pockets in which the metal would tend to accumulate thus forming a fluid coating for the walls of the jackheat, and also provides a material which will remain longer in suspension in the liquid vehicle because the Hat form of the flakes serves to retard their fall through the liquidtif there is a tendency for them to settle.

I claim l. A heat conducting medium comprising a quantity of aluminum in finely divided form and a relatively thin oil serving as a vehicle for said aluminum, together with a quantity of glycerine intermingled therewith and adapted to settle when the mixture is at rest. I

2. A heat conducting medium comprising a quantity of aluminum in the form of minute flat flakes. and a relatively thin oil serving as a vehicle therefor, together with a quantity of glycerine intermingled therewith and adapted .to settle more readily than the flakes of aluminum when the mixture is at rest. Y Y

3. A heat-conducting medium comprising a quantity of aluminum in finely divided form, a relatively thin oil serving as a vehicle therefor, and a liquid of greater densitythan the oil, said ingredients being intermingled normally, with the aluminum substantially carried in suspension, the heavier liquid being adapted to separate from the oil and settle more readily than the aluminum when the mixture is at rest.

4:. A heat-conducting medium com risin a quantity of aluminum in finely ivide form and a relatively thin oil serving as a vehicle for said aluminum.

5. A heat-conducting medium comprising with a liquid of greater density intermingled therewith and adapted to settle more rapidly than the metal when the mixture is at rest.

In testimony whereof, I have hereunto set my hand at Chicago, Illinois, this 12th day of November, 1926.

RALPH H. CHURCHILL.

a quantity of a. relatively light metal in finely divided form and a relatively thin oil serving as a vehicle therefor.

6. A heat-conducting medium comprising a quantity of a relatively light metal in finely divided form and a thin mineral oil serving as a vehicle therefor.

7 A heat-conducting medium comprisingv a quantity of a relatively light metal iii the form of minute flat flakes and a relatively thin oil serving as a vehicle therefor. I

8. A heat-conducting medium comprising a quantity of a relatively light metal in finely divided form and a relatively thin oil serving as a vehicle therefor, together 

